title: Predictors of blood loss and haematocrit after periacetabular osteotomy.
abstract: BACKGROUND
  Acetabular dysplasia is a common cause of hip pain that can lead to osteoarthritis. Periacetabular osteotomy (PAO) is an effective procedure to treat symptomatic dysplasia in properly selected patients.
  
  
  OBJECTIVE
  This study aims to determine patient or perioperative variables that are predictive of blood loss (EBL) and postoperative haematocrit (HCT) with PAO.
  
  
  METHODS
  Between March 2009 and October 2011, 169 PAOs in 141 patients were performed. Associations with EBL (log-transformed) and lowest postoperative haematocrit (post-HCT, <26 vs. ≥26) were assessed by regression analysis, adjusting for surgeon and for within-patient correlations.
  
  
  RESULTS
  Geometric mean EBL was 925 mL (range 200-3900 mL; 95% CI: 851.3, 1005.1). There was 11.1% greater blood loss per hour of surgery (p = 0.02). Preoperative HCT averaged (±SD) 36.1 (±3.3). In 119 cases (71%), the post-HCT was <26. Lower preoperative HCT correlated with post-HCT <26 (p<0.001); the median ratio of the lowest postoperative HCT to the preoperative HCT was 0.687 (5th, 95th percentiles: 0.538, 0.781). Age, body mass index (BMI), arthrotomy, and anaesthesia-type showed no association with EBL or post-HCT.
  
  
  CONCLUSIONS
  Longer duration of surgery correlated with increased blood loss during PAO. Current guidelines recommend considering transfusion at haemoglobin ≤8 g/dL for postoperative patients. The median nadir post-HCT was 31% lower than the preoperative value, a ratio that may help determine the need for preoperative blood donation. This information facilitates future investigation of blood management with PAO.
authors.affiliation: 1 Center for Hip Preservation, Department of Orthopaedics, Virginia Mason Medical Center, Seattle, Washington - USA.
authors.forename: Cara Beth
authors.initials: CB
authors.lastname: Lee
authors.forename: Leslie A
authors.initials: LA
authors.lastname: Kalish
authors.forename: Michael B
authors.initials: MB
authors.lastname: Millis
authors.forename: Young-Jo
authors.initials: YJ
authors.lastname: Kim
mesh_terms: D000077:Acetabulum / Q000601:surgery*; D000328:Adult; D005260:Female; D005500:Follow-Up Studies; D006400:Hematocrit / Q000379:methods; D006617:Hip Dislocation / Q000601:surgery*; D006801:Humans; D015994:Incidence; D008297:Male; D010027:Osteotomy / Q000009:adverse effects*; D019106:Postoperative Hemorrhage / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology; D011237:Predictive Value of Tests; D011379:Prognosis; D012189:Retrospective Studies; D012307:Risk Factors; D014481:United States / Q000453:epidemiology